1. Field of the Invention
The present invention relates to a camera device, and more particularly to an optical image stabilizer for a camera lens assembly.
2. Description of the Related Art
Generally, charge coupled device (CCD) sensors and complementary metal oxide semiconductor (CMOS) sensor are kinds of two-dimensional sensors for photographing dynamic and static images. They play a key role in constructing electronic cameras. Particularly, CCD sensors provide excellent characteristics compared to CMOS sensors in terms of image quality. However, CCD sensors have high power consumption and complicated structures. Thus, the market demand for CMOS image sensors has increased. Recently, many attempts have been made to improve image quality of CMOS sensors. As such image sensors are developed, use of digital cameras is generalized. For example, development in image sensors resulted in the production of portable terminals such as cellular phones equipped with camera devices.
Unstable images are frequently photographed with general cameras for photographing static and moving images using such image sensors, due to the trembling of cameras. For example, the trembling is the result from external causes, such as the user's trembling hands and mounting of cameras on vehicles. In order to solve the problem of unstable images, optical image stabilizers have been suggested. Such optical image stabilizers include a movement detector portion and a movement compensator portion.
For the movement detector, a method for predicting movements of a device by a Gyro Sensor, etc., as well as a method for detecting a moved portion of an image every frame by processing image signals is used. Additionally, it is possible to solve the problem of unstable images. Clear images is obtain using the movement-related information detected as described above. A refraction lens (active prism) is used, it optionally refracts the incident light or controls the input position of an image sensor.
U.S. Pat. No. 5,398,132 (published on Mar. 14, 1995) discloses an optical image stabilizer. A lens is driven using a voice coil motor to solve the problem of unstable images resulting from movements of a camera. Such an optical image stabilizer includes a pitch coil and a pitch yoke disposed on one side of a compensator lens for driving the compensator lens in one direction as well as a yaw coil and a yaw yoke disposed on the other side of the compensator lens for driving the compensator lens in another direction perpendicular to the first direction. Briefly, in such an optical image stabilizer the compensator lens is moved according to movements of a camera so as to return an optical axis to its original position, thereby stabilizing images.
Recently, portable terminals tend to have extended functions due to a camera device mounted on portable terminals such as laptop computers and portable phones. However, conventional optical image stabilizers hinder portable terminals from being downsized and lightened.